Surging flow for bubble clearing in electroplating systems

ABSTRACT

Exemplary methods of semiconductor processing may include performing an electroplating operation on a semiconductor substrate in an electroplating bath within a vessel of an electroplating system. The methods may include removing the semiconductor substrate from the electroplating bath. The methods may include closing a valve associated with a first drain from the electroplating system. The methods may include increasing flow to a second drain from the electroplating system. The second drain may be associated with a drain channel from the vessel of the electroplating system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application 63/303,154 filed Jan. 26, 2022, entitled “SURGING FLOW FOR BUBBLE CLEARING IN ELECTROPLATING SYSTEMS,” the entire disclosure of which is hereby incorporated by reference, for all purposes, as if fully set forth herein.

TECHNICAL FIELD

The present technology relates to electroplating operations in semiconductor processing. More specifically, the present technology relates to systems and methods that perform bubble removal and clearing for electroplating systems.

BACKGROUND

Integrated circuits are made possible by processes which produce intricately patterned material layers on substrate surfaces. After formation, etching, and other processing on a substrate, metal or other conductive materials are often deposited or formed to provide the electrical connections between components. Because this metallization may be performed after many manufacturing operations, problems occurring during the metallization may create expensive waste substrates or wafers.

Electroplating is performed in an electroplating chamber with the device side of the wafer in a bath of liquid electrolyte, and with electrical contacts on a contact ring touching a conductive layer on the wafer surface. Electrical current is passed through the electrolyte and the conductive layer. Metal ions in the electrolyte plate out onto the wafer, creating a metal layer on the wafer. Air or other bubbles along a surface of the electroplating bath fluid may prevent plating at locations where the bubbles interrupt fluid contact with the substrate surface. Bubbles may be formed along the surface of the plating bath from any number of sources during plating processes.

Thus, there is a need for improved systems and methods that can be used to produce high quality devices and structures while protecting both the substrate and the plating baths. These and other needs are addressed by the present technology.

SUMMARY

Exemplary methods of semiconductor processing may include performing an electroplating operation on a semiconductor substrate in an electroplating bath within a vessel of an electroplating system. The methods may include removing the semiconductor substrate from the electroplating bath. The methods may include closing a valve associated with a first drain from the electroplating system. The methods may include increasing flow to a second drain from the electroplating system. The second drain may be associated with a drain channel from the vessel of the electroplating system.

In some embodiments, the vessel may include a weir about the vessel, and increasing flow to the second drain may increase flow over the weir into the drain channel providing access to the second drain. The weir may define a plurality of notches extending from an upper surface of the weir. The vessel may include an upper cup defining a plurality of channels through an upper surface of the upper cup. One or more apertures may couple each channel of the plurality of channels with a volume within the vessel in fluid contact with a membrane. A catholyte may be flowed within the volume. The volume may be in contact with a first surface of the membrane. The methods may include flowing an anolyte in contact with a second surface of the membrane opposite the first surface of the membrane. The first drain may be associated with one or more outlets of the volume within the vessel. A central channel may be defined through the upper cup. Catholyte may be flowed into the vessel through the upper cup. While performing the electroplating operation, catholyte flow may extend both into each channel of the plurality of channels and over a weir extending about the vessel. The electroplating system may include a return pump fluidly coupled with the second drain. The electroplating system may include a level sensor disposed within the drain channel. The level sensor may be communicatively coupled with the return pump. The return pump may be operable to increase a flow rate from the second drain in response to a signal from the level sensor indicating an increase in catholyte level within the drain channel.

Some embodiments of the present technology may encompass methods of semiconductor processing. The methods may include performing an electroplating operation on a semiconductor substrate in an electroplating bath within a vessel of an electroplating system. The methods may include removing the semiconductor substrate from the electroplating bath. The methods may include diverting flow to a first drain from the electroplating system. The methods may include increasing flow to a second drain from the electroplating system. The second drain may be associated with a drain channel from the vessel of the electroplating system. Increasing flow to the second drain may occur for a first period of time. The methods may include reducing flow to the second drain from the electroplating system after the first period of time.

In some embodiments, while reducing flow to the second drain after the first period of time, the methods may include increasing flow to the first drain. The vessel may include a weir about the vessel. Increasing flow to the second drain may increase flow over the weir into the drain channel providing access to the second drain. The weir may define a plurality of notches extending from an upper surface of the weir. The vessel may include an upper cup defining a plurality of channels through an upper surface of the upper cup. One or more apertures may couple each channel of the plurality of channels with a volume within the vessel in fluid contact with a membrane. A central channel may be defined through the upper cup. Catholyte may be flowed into the vessel through the upper cup. While performing the electroplating operation, catholyte flow may extend both into each channel of the plurality of channels and over the weir. While increasing flow to the second drain, a height of catholyte may increase within the drain channel by less than or about 2 cm. The first period of time may be less than or about 30 seconds.

Some embodiments of the present technology may encompass methods of semiconductor processing comprising. The methods may include performing an electroplating operation on a semiconductor substrate in an electroplating bath within a vessel of an electroplating system. The vessel may include a weir about the vessel. The methods may include removing the semiconductor substrate from the electroplating bath. The methods may include providing a first flow through the electroplating system through a central channel through the vessel. The methods may include providing a second flow through the electroplating system through secondary channels through the vessel and radially outward of the central channel. The first flow and the second flow may extend to a drain channel from the vessel of the electroplating system. The flow to the drain channel may extend over the weir into the drain channel, which may provide access to a drain. In some embodiments, the weir may define a plurality of notches extending from an upper surface of the weir. While increasing flow to the second drain, a height of catholyte within the drain channel may increase by less than or about 2 cm.

Such technology may provide numerous benefits over conventional technology. For example, the present technology may reduce or limit bubbles along the meniscus of the plating bath during electroplating processes. Additionally, the systems may also clear bubbles with minimal time loss between subsequent plating operations, while also limiting retrofit components or costs related to the improved clearing ability. These and other embodiments, along with many of their advantages and features, are described in more detail in conjunction with the below description and attached figures.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the disclosed embodiments may be realized by reference to the remaining portions of the specification and the drawings.

FIG. 1 shows a schematic view of an electroplating processing system according to some embodiments of the present technology.

FIG. 2 shows a cross-sectional view of a portion of an electroplating processing system according to some embodiments of the present technology.

FIG. 3 shows exemplary operations in a method of operating an electroplating system according to some embodiments of the present technology.

FIG. 4 shows a schematic cross-sectional view of a portion of an electroplating processing system according to some embodiments of the present technology.

FIG. 5 shows a schematic perspective view of a slotted weir according to some embodiments of the present technology.

FIG. 6 shows exemplary operations in a method of operating an electroplating system according to some embodiments of the present technology.

Several of the figures are included as schematics. It is to be understood that the figures are for illustrative purposes, and are not to be considered of scale unless specifically stated to be of scale. Additionally, as schematics, the figures are provided to aid comprehension and may not include all aspects or information compared to realistic representations, and may include exaggerated material for illustrative purposes.

In the figures, similar components and/or features may have the same numerical reference label. Further, various components of the same type may be distinguished by following the reference label by a letter that distinguishes among the similar components and/or features. If only the first numerical reference label is used in the specification, the description is applicable to any one of the similar components and/or features having the same first numerical reference label irrespective of the letter suffix.

DETAILED DESCRIPTION

Various operations in semiconductor manufacturing and processing are performed to produce vast arrays of features across a substrate. As layers of semiconductors are formed, vias, trenches, and other pathways are produced within the structure. These features may then be filled with a conductive or metal material that allows electricity to conduct through the device from layer to layer.

Electroplating operations may be performed to provide conductive material into vias and other features on a substrate. Electroplating utilizes an electrolyte bath containing ions of the conductive material to electrochemically deposit the conductive material onto the substrate and into the features defined on the substrate. The substrate on which metal is being plated operates as the cathode. An electrical contact, such as a ring or pins, may allow the current to flow through the system. During electroplating, a substrate may be clamped to a head and submerged in the electroplating bath to form the metallization. Metal ions may be deposited on the substrate from the bath.

In plating systems utilizing an inert anode, an additional source of metal ions may be used to replenish a catholyte solution. The metal ions may be transferred into the catholyte across a membrane and from an anolyte solution. The catholyte and anolyte both may be flowed across opposite sides of the membrane, which may be configured to allow the transmission of metal ions from the anolyte to the catholyte, while limiting transmission of additives and other materials from the catholyte into the anolyte. The catholyte may then be circulated across the substrate surface during plating to allow the metal ions to plate out against the substrate and form conductive structures.

Air bubbles within the catholyte or electroplating bath may cause issues with plating. When a substrate is submerged in the bath, an air bubble trapped against the surface of the substrate may prevent the catholyte from contacting the surface in that location, which may prevent plating at that location, and which can cause defects or device failure. Clearing bubbles from the meniscus across the bath surface may be challenged by a number of processing aspects. For example, when the substrate is removed from the bath, falling liquid back into the bath may cause bubbles to form on the surface. Similarly, subsequent rinsing operations may cause droplets to fall to the bath surface and form bubbles. Finally, air entrained within the catholyte may cause bubbles in the delivery if not previously removed. While conventional technologies have tried to limit the formation of bubbles on the surface, bubbles continue to be a challenge to electroplating operations.

The present technology overcomes these issues by surging catholyte liquid through the electroplating chamber after an electroplating operation, which may facilitate drawing bubbles from the surface of the liquid and delivering them out of the plating vessel. By limiting or negating competing forces that may keep bubbles within the vessel, as will be explained further below, clearing bubbles from the plating bath according to some embodiments of the present technology may improve plating operations, while limiting time between plating operations. After describing an exemplary system in which embodiments of the present technology may be incorporated, the remaining disclosure will discuss aspects of the systems and processes of the present technology.

FIG. 1 shows a schematic view of an electroplating system 20 according to some embodiments of the present technology. The system may include one or more components as discussed below for processing substrates. It is to be understood that electroplating system 20 is included as an example of electroplating systems that may benefit from one or more aspects of the present technology. The figure may provide general structures discussed further below. As shown, electroplating system 20 may include a head 30 positioned above a vessel assembly 50. The vessel assembly 50 may be supported on deck plate 24 and a relief plate attached to a stand 38 or other structure. A single electroplating system 20 may be used as a standalone unit, or multiple electroplating systems 20 may be provided in arrays, with workpieces or substrates loaded and unloaded in and out of the processors by one or more robots. Head 30 may be supported on a lift/rotate unit 34, which may be operated to lift and invert the head to load and unload a workpiece into the head, and for lowering the head 30 into engagement with the vessel assembly 50 for processing.

Electrical control and power cables 40 linked to the lift/rotate unit 34 and to internal head components may lead up from the electroplating system 20 to facility connections, or to connections within a multi-processor automated system. A rinse assembly 28 having tiered drain rings may be provided above the vessel assembly 50. A drainpipe 42 may connect the rinse assembly 28, if used, to a facility drain. An optional lifter 36 may be provided underneath the vessel assembly 50, and which may support the anode cup during changeover of the anodes. Alternatively, the lifter 36 may be used to hold the anode cup up against the rest of the vessel assembly 50.

Turning to FIG. 2 is shown a cross-sectional view of a portion of an electroplating processing system according to some embodiments of the present technology, and which may show further details of electroplating system 20 discussed above. As illustrated, the vessel assembly 50 may include an anode cup 52, a lower membrane support 54, and an upper membrane support 56 held together with fasteners, bolts, or any other mechanism for mechanically coupling the components. Within the anode cup 52, a first or inner anode 70 may be positioned near the bottom of an inner anolyte chamber or volume formed between the inner anode and a backside of a membrane 85. A second or outer anode 72 may be positioned near the bottom of an outer anolyte chamber or volume surrounding the inner anolyte chamber, and the outer anolyte chamber may also be formed between the outer anode and a backside of membrane 85. The inner anode 70 may be a flat round metal plate, and the outer anode 72 may be a flat ring-shaped metal plate, for example, and which may include a platinum-plated titanium plate, or any number of other materials according to embodiments of the present technology.

The inner and outer anolyte chambers may be filled with copper pellets, or may be fluidly coupled, such as with piping, pumps, valves, or other components, with a facilities cabinet, which may include copper pellets or some other material which may provide metal ions for plating operations according to the present technology, and which may be used for plating copper or any other metal or material used in semiconductor processing. As shown in FIG. 2 , the inner anode 70 may be electrically coupled with a first electrical lead or connector 130 and the outer anode 72 may be electrically connected to a separate second electrical lead or connector 132. Unlike many conventional designs, in some embodiments of the present technology, the electroplating system may have a center anode, and only a single outer anode, yet still achieve improved performance due to other design features. Having only two anodes, instead of three or more anodes, may simplify the design and control of the system, and may also reduce the overall cost and complexity of the system. It is to be understood that designs including three or more anodes may also optionally be used, such as with larger substrates, for example.

An upper cup 76 may be contained within or surrounded by an upper cup housing 58, or chamber body, and the upper cup 76 may be part of a vessel in which a substrate may be disposed to perform electroplating operations. The upper cup housing 58 may be attached to and sealed against the upper cup 76. The upper cup 76 may have a curved top surface 124 and a central aperture or opening that may form a central or inner vessel 120, into which catholyte may be flowed. This vessel 120 may be defined by the generally cylindrical space within a diffuser 74 leading into the bell or horn-shaped space defined by the curved upper surface 124 of the upper cup 76. A series of concentric annular slots may extend downwardly from the top curved surface 124 of the upper cup 76. An outer catholyte chamber 78, or volume as described further below, may be formed in the bottom of the upper cup 76, and which may be connected to the rings via an array of tubes or other passageways.

The diffuser 74 may be positioned within a central opening of the upper cup 76 and may be surrounded by a diffuser shroud 82. A first or inner membrane 85 may be secured between the upper and lower membrane supports 54 and 56, and may separate the inner anolyte chamber from the vessel 120. An inner membrane support 88, which may be provided in the form of radial spokes 114 centrally located on the upper membrane support 56, may support the inner membrane 85 from above. This design may leave the vessel 120 substantially open, which may better allow high current flow from the inner anode to the workpiece while plating onto resistive films. The radial spokes may occupy or block less than about 5%, 10%, 15% or 20% of the cross-sectional area of the vessel 120. Similarly, a second or outer membrane 86 may be secured between the upper and lower membrane supports and separate the outer anolyte chamber from the outer catholyte chamber 78. An outer membrane support 89, which may be provided in the form of radial legs 105 or 116 on the upper membrane support 56, may support the outer membrane from above.

A diffuser circumferential horizontal supply duct 84 may be formed in an outer cylindrical wall of the upper cup 76, with the duct 84 sealed by O-rings or similar elements between the outer wall of the upper cup 76 and the inner cylindrical wall of the upper cup housing 58. As shown in the figure, radial supply ducts 80 may extend radially inwardly from the circumferential duct 84 to an annular shroud plenum 87 surrounding the upper end of the diffuser shroud 82. The radial ducts 80 may pass through the upper cup 76 in between the vertical tubes connecting the annular slots in the curved upper surface 124 of the upper cup 76 to the outer catholyte chamber 78. A current thief assembly 200 may be included, and which may include a thief electrode and receive an electrolyte or thiefolyte, which in operation may help improve control of edge plating and improve plating uniformity.

During operation, anolyte may be provided into the inner anolyte chamber via a more central inlet through the base of the structure. Anolyte may be provided into the outer anolyte chamber via a radially outer inlet through the base of the structure. Anolyte may flow out of the inner anolyte chamber via a circulation slot 162, and anolyte may flow out of the outer anolyte chamber via a circulation slot 160. Additionally, catholyte may flow up and radially outwardly in the vessel 120. The flow may continue to spill over a weir 68, which may extend about the vessel, and may deliver catholyte into a drain channel 122. Catholyte may flow out of the drain channel 122 to a return port for recirculation. A catholyte level indicator 140 may monitor the catholyte liquid level within the drain channel 122 and/or the upper cup 76. The indicator 140 may be communicatively coupled with a return pump, as will be shown below, which may be ramped to higher or lower speed to control a catholyte level. It is to be understood that the terms anolyte and catholyte as used here refer to the location of the electrolyte in the processor, and not necessarily to any specific chemical makeup of the electrolyte.

FIG. 3 shows exemplary operations in a method 300 of operating an electroplating system according to some embodiments of the present technology. The method may be performed in a variety of processing systems, including electroplating system 20 described above, or any other electroplating system, and which may include any of the components, assemblies, or subsystems previously described. Method 300 may be performed to limit bubble formation along a surface of the catholyte, or meniscus, and which may improve plating uniformity across a wafer. Method 300 may include a number of optional operations, which may or may not be specifically associated with some embodiments of methods according to the present technology. Method 300 may be described in conjunction with the system illustrated in FIG. 4 , which shows a schematic cross-sectional view of a portion of an electroplating system 400 according to some embodiments of the present technology. Electroplating system 400 may schematically show some of the components of electroplating system 20, including the vessel assembly 50 described above, and which may be included to facilitate a discussion of the operations being performed, and with no intention of limiting the technology to the schematics shown. It is to be understood that electroplating system 400 may include any of the components previously described, as well as any number of other components commonly used in electroplating systems.

For example, and as discussed in more detail above, electroplating system 400 may include a vessel 405, which may contain an electroplating bath, such as catholyte, and which may be sized to receive a substrate or wafer for plating. The vessel may be defined by one or more components as discussed above, such as including an upper cup 410 and a weir 415. Catholyte may be flowed up through a central channel of the upper cup as shown, and may flow radially outward within the vessel. As described above, catholyte may flow in multiple directions within the vessel. The flow may extend over weir 415 into a drain channel 420 formed within the chamber housing, and extending about the vessel, such as externally to the upper cup 410 and the weir 415. Additionally, the catholyte may flow through the channels formed through the upper cup from an upper surface of the upper cup, and through apertures 422 formed from the channels through the base of the upper cup into a volume 425 defined beneath the upper cup 410. Volume 425 may be between the upper cup and a membrane 430, where the volume may be against a first surface of membrane 430. As shown, catholyte may flow through the channels and apertures into the volume, and may sweep along the membrane 430 to receive metal ions from an anolyte. An anolyte may be flowed through a volume 435 along a second surface of the membrane 430, such as a surface opposite the first surface, and which may allow the anolyte to pass metal ions to the catholyte through the membrane.

Catholyte may exit the system from multiple locations. For example, from volume 425, one or more first drains 427 may be coupled with the volume and operate as outlets, and may retrieve catholyte from the volume. For example, any number of drains may provide flow from the volume 425, and may extend to a valve 440, which may control flow from the first drains, and may provide catholyte to a bath 445, or some other retrieval system for replenishment and/or redelivery into the central channel through the upper cup, and into the vessel. Additionally, once received in the drain channel 420, catholyte may be flowed through a second drain 450, and pumped back to catholyte bath 445, such as with return pump 455. These flows may be controlled to a steady state position to form a meniscus 460 across the top of the vessel, and maintained by overflow across the weir. A substrate may then be delivered into the bath for plating.

As noted above, catholyte may be circulated within the lower volume beneath the upper cup, and in ionic communication with the anolyte. Circulation of catholyte within this volume may help to limit crystallization within the anolyte. For example, without proper circulation of the catholyte to receive ions from the anolyte, the anolyte may become supersaturated near the membrane, which may cause crystals to form in the anolyte, and which may reduce the ions available for plating onto a wafer or substrate. Accordingly, catholyte may be flowed at a rate to ensure proper transfer of the metal ions. However, this flow may present force against the flow over the weir, which may cause eddies or ripples to form across the meniscus, and which may cause air to be trapped between the substrate and the catholyte, challenging plating at those locations. Additionally, this flow may cause bubbles to be trapped along a surface of the meniscus, which may again become trapped against the substrate and limit plating at that location.

As explained above, when a substrate is removed from the plating bath after an electroplating operation, catholyte or electrolyte bath fluid may fall back into the vessel, causing bubbles to form along the surface. These bubbles should flow along with the catholyte over the weir and be removed from plating bath, without being entrained in the system. However, due to the catholyte flow through the upper cup, bubbles may be caught in eddies along the meniscus, and flow over the weir may not draw these bubbles from the system. The present technology may adjust flow within the vessel to increase flow over the weir, which may improve bubble removal from the system. Simply increasing an inlet flow rate may be insufficient to resolve the bubble retainment due to the competing flow through the upper cup. For example, if inlet flow is simply increased by a certain amount, flow through the upper cup may also increase, which may increase the force along the meniscus, and may exacerbate the flow characteristics and bubble retainment. Accordingly, the present technology may both alter flow through the upper cup, as well as increase flow over the weir, which may help draw bubbles from the surface, and ensure a better meniscus for subsequent processing.

Method 300 may include operations to facilitate bubble removal from the plating bath, and may be performed during or between wafer plating processes. For example, at optional operation 305, an electroplating operation may be performed on a semiconductor substrate submerged within the plating bath, or catholyte. Once completed, the substrate may be removed or withdrawn from the electroplating bath at operation 310. This operation, as well as rinsing operations performed on the substrate, may cause fluid droplets back into the bath, and may cause bubble formation as discussed above. Method 300 may then adjust catholyte flow through the system to improve bubble removal before a subsequent wafer is disposed in the bath for plating.

Method 300 may include diverting flow through the first drains at operation 315. Diverting the flow may occur in any number of ways, and in systems including a valve to which each of the drains flows, such as valve 440 discussed previously, the flow from the first drains may be reduced by at least partially closing the valve, and may include fully shutting the valve in some embodiments. This may halt any countervailing flow within the vessel, and flow all fluid over the weir, which may reduce turbulent interference, and more laminarly flow all fluid over the weir into the drain channel. Additionally, as inlet flow may be maintained or increased in some embodiments, flow to the drain channel, and the second drain, may be increased at operation 320. In some embodiments the inlet flow may not be increased, and the increased flow may be only from the lack of additional drain paths. This may control the amount of fluid level rise within the drain channel, which may limit time losses to return to steady operation.

For example, the increased second flow, or flow over the weir, may be performed for a first amount of time, after which the valve may be returned to a prior operating position or opening, which may increase the flow from the first drain or drains. This may cause the second flow to decrease or reduce, such as at optional operation 325, as the system returns to previous levels. By controlling the amount of additional flow over the weir, and ensuring the volume in the drain channel is allowed to properly reduce, improved performance may be afforded as liquid level within the drain channel may directly affect system operation. For example, as the flow over the weir is allowed to increase to remove bubbles, liquid level in the drain channel may rise from a first level 470 a to a second level 470 b, which may be relative and illustrated only as an example, and not necessarily as specific levels. When a substrate is delivered into the bath, a large volume of catholyte fluid may be forced over the weir and into the drain channel. If the fluid level within the drain channel is not allowed to reduce prior to delivery of a subsequent wafer, splashing or overflow onto the head or other system components may occur, which may cause damage to equipment.

As stated above, a liquid level sensor 475 may be disposed within the drain channel 420, and may monitor the fluid level. The sensor may be communicatively coupled with the return pump 455, which may be ramped higher or lower to increase or decrease flow from the drain channel in response to receiving a signal from the level sensor indicating an increase or decrease in catholyte level within the drain channel. However, simply ramping the pump to overcome the fluid increase may similarly be insufficient. For example, the pump may not be sized to overcome the volume change based on the increased flow over the weir, which may cause the fluid level to rise. Additionally, too high an increased removal rate may cause the liquid level within the drain channel to fall too low, which may allow air to be entrained within the system. Accordingly, in some embodiments, the inlet delivery rate may be maintained during method 300, and a second period of time may occur prior to delivery of a subsequent wafer, and during which time the liquid level in the drain channel may be lowered to a level similar to a level prior to the first period of time. This may ensure uniform processing conditions between wafers, while still allowing bubbles to be removed from the system.

The first time period may begin at any point after an electroplating operation has finished, and may begin as soon as a substrate is withdrawn from the vessel and plating bath. Once all flow or increased flow extends over the weir, the drain channel may be overwhelmed after a sufficient time period, and thus, the first time period may be limited to clear bubbles while ensuring the drain channel does not overly fill. To limit the opportunity to overwhelm the drain channel and to limit throughput losses during performance of the method, the first period of time may be maintained at less than or about 60 seconds, and may be maintained at less than or about 55 seconds, less than or about 50 seconds, less than or about 45 seconds, less than or about 40 seconds, less than or about 35 seconds, less than or about 30 seconds, less than or about 25 seconds, less than or about 20 seconds, less than or about 15 seconds, less than or about 10 seconds, less than or about 5 seconds, or less.

The second period of time may be any of these stated time periods, and may be the same, greater than, or less than the amount of time of the first time period. Accordingly, the entire process of increasing flow over the weir to remove bubbles and then allowing the system to return to pre-processing conditions after the flow to the first drains has fully resumed may be less than or about 2 minutes, and may be less than or about 90 seconds, less than or about 60 seconds, less than or about 50 seconds, less than or about 40 seconds, less than or about 30 seconds, less than or about 20 seconds, less than or about 10 seconds, or less. By controlling the time and inlet flow for the method, as well as pumping speed for the return pump, a liquid level within the drain channel during the method may not rise greater than or about 5 cm, and may not rise greater than or about 4 cm, greater than or about 3 cm, greater than or about 2 cm, greater than or about 1 cm, greater than or about 9 mm, greater than or about 8 mm, greater than or about 7 mm, greater than or about 6 mm, greater than or about 5 mm, greater than or about 4 mm, greater than or about 3 mm, or less.

In some embodiments, one or more components may also facilitate bubble removal from the system. FIG. 5 shows a schematic perspective view of a slotted weir 500 according to some embodiments of the present technology. Weir 500 may be used in place of any weir discussed previously, including weir 68 and weir 415, for example. Weir 500 may be castellated, and may have one or more slots or notches 505 formed from an upper surface of the weir, and extending at least partially through the outer edge of the weir. This may improve fluid flow over the weir, and may improve bubble removal in some embodiments. Although weirs characterized by a uniform, flat exterior profile may be used in embodiments of the present technology, a slotted weir may limit dry spots and increase flow at the slot locations. For example, on a flat weir, flow over the edge may not be uniform about the weir, and bubbles may collect at locations where flow does not carry over the edge of the weir. However, the notches may reduce surface tension and increase surface flow at each notch location. This may further improve bubble removal by causing increased flow rate at the location of each notch, pulling the fluid over or through the weir. Accordingly, in some embodiments a slotted weir may be utilized to further improve bubble removal from the system.

Some embodiments of the present technology may further increase flow over the weir by reversing flow through the upper cup so that both flows extend over the weir. FIG. 6 shows exemplary operations in a method 600 of operating an electroplating system according to some embodiments of the present technology. Method 600 may be performed in any of the systems previously described, and may include any of the operations discussed with regard to method 300. For example, method 600 may optionally include performing an electroplating operation 605, and removing a substrate from the plating bath and vessel at operation 610. In some embodiments, method 600 may cause both flow paths to extend over the weir. For example, as previously described, at operation 615, a first flow may extend through the central channel of the upper cup and over the weir. Additionally, in some embodiments, a secondary pump 480 may be included in the system, and may be engaged to cause a second flow at operation 620 to deliver catholyte back through valve 440 and into drains 427. The flow may then be forced up through the apertures and channels in the upper cup, such as along flow path 485, which may further increase flow over the weir, and which may provide uniform direction of flow through the chamber, which may improve bubble removal from the system. Although discussed as operations, it is to be understood that the flows may be performed during plating operations and subsequent, or the second flow may be reversed subsequent to electroplating in some embodiments.

By reversing the flow through the first drains compared to the previously described process, flow across the membrane may be maintained during the bubble removal process, which may ensure ionic transport across the membrane may not be impacted by the process. The process may be performed for any length of time, such as any time period specified above. By performing flow adjustments according to embodiments of the present technology, bubble removal may be improved compared to conventional systems, while limiting an effect on processing throughput. Additionally, the present technology may readily be retrofitted to existing systems, which may not require component replacement or system reconfiguration in some embodiments.

In the preceding description, for the purposes of explanation, numerous details have been set forth in order to provide an understanding of various embodiments of the present technology. It will be apparent to one skilled in the art, however, that certain embodiments may be practiced without some of these details, or with additional details. For example, other substrates that may benefit from the wetting techniques described may also be used with the present technology.

Having disclosed several embodiments, it will be recognized by those of skill in the art that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the embodiments. Additionally, a number of well-known processes and elements have not been described in order to avoid unnecessarily obscuring the present technology. Accordingly, the above description should not be taken as limiting the scope of the technology.

Where a range of values is provided, it is understood that each intervening value, to the smallest fraction of the unit of the lower limit, unless the context clearly dictates otherwise, between the upper and lower limits of that range is also specifically disclosed. Any narrower range between any stated values or unstated intervening values in a stated range and any other stated or intervening value in that stated range is encompassed. The upper and lower limits of those smaller ranges may independently be included or excluded in the range, and each range where either, neither, or both limits are included in the smaller ranges is also encompassed within the technology, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included. Where multiple values are provided in a list, any range encompassing or based on any of those values is similarly specifically disclosed.

As used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. Thus, for example, reference to “a material” includes a plurality of such materials, and reference to “the channel” includes reference to one or more channels and equivalents thereof known to those skilled in the art, and so forth.

Also, the words “comprise(s)”, “comprising”, “contain(s)”, “containing”, “include(s)”, and “including”, when used in this specification and in the following claims, are intended to specify the presence of stated features, integers, components, or operations, but they do not preclude the presence or addition of one or more other features, integers, components, operations, acts, or groups. 

What is claimed is:
 1. A method of semiconductor processing comprising: performing an electroplating operation on a semiconductor substrate in an electroplating bath within a vessel of an electroplating system; removing the semiconductor substrate from the electroplating bath; closing a valve associated with a first drain from the electroplating system; and increasing flow to a second drain from the electroplating system, wherein the second drain is associated with a drain channel from the vessel of the electroplating system.
 2. The method of semiconductor processing of claim 1, wherein the vessel comprises a weir about the vessel, and wherein increasing flow to the second drain increases flow over the weir into the drain channel providing access to the second drain.
 3. The method of semiconductor processing of claim 2, wherein the weir defines a plurality of notches extending from an upper surface of the weir.
 4. The method of semiconductor processing of claim 1, wherein the vessel includes an upper cup defining a plurality of channels through an upper surface of the upper cup, and wherein one or more apertures couples each channel of the plurality of channels with a volume within the vessel in fluid contact with a membrane.
 5. The method of semiconductor processing of claim 4, wherein a catholyte is flowed within the volume, and wherein the volume is in contact with a first surface of the membrane.
 6. The method of semiconductor processing of claim 5, further comprising: flowing an anolyte in contact with a second surface of the membrane opposite the first surface of the membrane.
 7. The method of semiconductor processing of claim 5, wherein the first drain is associated with one or more outlets of the volume within the vessel.
 8. The method of semiconductor processing of claim 5, wherein a central channel is defined through the upper cup, wherein catholyte is flowed into the vessel through the upper cup, and wherein, while performing the electroplating operation, catholyte flow extends both into each channel of the plurality of channels and over a weir extending about the vessel.
 9. The method of semiconductor processing of claim 1, wherein the electroplating system further comprises: a return pump fluidly coupled with the second drain; and a level sensor disposed within the drain channel, wherein the level sensor is communicatively coupled with the return pump.
 10. The method of semiconductor processing of claim 9, wherein the return pump is operable to increase a flow rate from the second drain in response to a signal from the level sensor indicating an increase in catholyte level within the drain channel.
 11. A method of semiconductor processing comprising: performing an electroplating operation on a semiconductor substrate in an electroplating bath within a vessel of an electroplating system; removing the semiconductor substrate from the electroplating bath; diverting flow to a first drain from the electroplating system; increasing flow to a second drain from the electroplating system, wherein the second drain is associated with a drain channel from the vessel of the electroplating system, wherein increasing flow to the second drain occurs for a first period of time; and reducing flow to the second drain from the electroplating system after the first period of time.
 12. The method of semiconductor processing of claim 11, further comprising, while reducing flow to the second drain after the first period of time: increasing flow to the first drain.
 13. The method of semiconductor processing of claim 11, wherein the vessel comprises a weir about the vessel, and wherein increasing flow to the second drain increases flow over the weir into the drain channel providing access to the second drain.
 14. The method of operating an electroplating system of claim 13, wherein the weir defines a plurality of notches extending from an upper surface of the weir.
 15. The method of operating an electroplating system of claim 13, wherein the vessel includes an upper cup defining a plurality of channels through an upper surface of the upper cup, and wherein one or more apertures couples each channel of the plurality of channels with a volume within the vessel in fluid contact with a membrane.
 16. The method of operating an electroplating system of claim 15, wherein a central channel is defined through the upper cup, wherein catholyte is flowed into the vessel through the upper cup, and wherein, while performing the electroplating operation, catholyte flow extends both into each channel of the plurality of channels and over the weir.
 17. The method of semiconductor processing of claim 11, wherein, while increasing flow to the second drain, a height of catholyte increases within the drain channel by less than or about 2 cm.
 18. The method of semiconductor processing of claim 11, wherein the first period of time is less than or about 30 seconds.
 19. A method of semiconductor processing comprising: performing an electroplating operation on a semiconductor substrate in an electroplating bath within a vessel of an electroplating system, wherein the vessel comprises a weir about the vessel; removing the semiconductor substrate from the electroplating bath; providing a first flow through the electroplating system through a central channel through the vessel; and providing a second flow through the electroplating system through secondary channels through the vessel and radially outward of the central channel, wherein the first flow and the second flow extend to a drain channel from the vessel of the electroplating system, and wherein the flow to the drain channel extends over the weir into the drain channel, which provides access to a drain.
 20. The method of semiconductor processing of claim 19, wherein the weir defines a plurality of notches extending from an upper surface of the weir, and wherein, while increasing flow to the second drain, a height of catholyte within the drain channel increases by less than or about 2 cm. 